A petroleum resin allows a low-molecular compound which is a highly-viscous fine particle such as an oligomer to be generated in a polymer in its polymerization system as an impurity. The low-molecular compound is separated and generated as a low-molecular mist in a granulation system, in particular.
For example, a hydrogenated petroleum resin is produced by a process in which polymerization is conducted in a polymerization system, followed by removal of unsaturated matters in the resin in a hydrogenation reaction system. At this time, for a resin from which unsaturated matters are removed, a solvent and a low-molecular compound are removed by a thin film evaporator. In the molten state, the resin is sent to a granulation system as a final process to become a hydrogenated petroleum resin pellet.
The above-mentioned molten hydrogenated petroleum resin contains a trace amount of a low-molecular compound which cannot be separated by a thin film evaporator. In the hydrogenated molten petroleum resin containing the low-molecular compound, at the time of dropwise addition thereof to a steel belt at the time of granulation, as for the low-molecular compound, a smoke-like mist is generated from the surface of the resin. This mist is sucked together with cooling air by means of a blower, and then discharged to the outside from an exhaustion port through an exhaustion duct, thereby imposing environmental load.